Biodegradable quaternary ammonium salts such as N,N-di(tallowoyloxyethyl)-N,N,-dimethylammonium chloride and 1,2-ditallowyloxy-3-trimethylammonio propane chloride have been developed as described in U.S. Pat. Nos. 4,137,180; 4,767,547 and 4,789,491.
Because of softening properties and ease of processing, a preferred biodegradable quaternary ammonium salt is a diester compound of the formula described in Column 1 of U.S. Pat. No. 4,137,180.
It has been discovered, however, that many of the diester compounds described above degrade to a monoester form which in certain levels can be aquatically toxic. Moreover, when the diester compounds are processed with relatively large quantities of alcohol the obtained compounds are more likely to form monoester degradation intermediates.
Thus, the need exists for novel fabric conditioning agents whose degradation products do not form monoester quaternary intermediates and thus are also environmentally friendly.